ACTG 315 - A Pilot Study to Evaluate the Immunologic Consequences of a Highly Active Anitretroviral Therapy Regimen (HAARTR) Consisting of Ritonavir (ABT-538), Zidovudine (ADV), and Lamivudine (3TC) in Moderately Advanced HIV-1 Disease; This study explored whether administration of a highly active antiretroviral treatment regimen (HAARTR) consisting of ritonavir (ABT-538), zidovudine (ZDV), and lamivudine (3TC) in combination would restore delayed type hypersensitivity and lymphocyte proliferative responses in subjects with moderately advanced HIV-1 infection. The study also examined whether cells of the monocyte/macrophage lineage represent a reservoir of HIV-1 infection that continues low-level production of virus after initiation of antiretroviral therapy. This study was a 48-week, open-label pilot trial of a HAARTR consisting of ritonavir, zidovudine, and lamivudine. Forty-eight evaluable subjects with moderately advanced HIV-1 infection (CD4+ cell count between 100-300 cells/mm3) received the following open label treatment regimen for 48 weeks: Ritonavir 300mg BID for two days, then Ritonavir 400mg BID for two days, then Ritonavir 500 mg BID for two days, then, Ritonavir 600 mg BID for three days. On Study Day 10 and through Week 48, the treatment regimen consisted of: ritonavir 600 mg BID plus zidovudine 300 mg TID plus lamivudine 150mg BID. 48-week data has been analyzed.